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I have one of those MacBook Pro's (2015) with the hardware fault which causes frequent spontaneous shutdowns.

The problem can be solved by renaming or deleting AppleThunderboltNHI.kext which I have done after every MacOS Catalina update for the past couple of years, basically everything except step 7 & 8 below.

In Big Sur, the change doesn't "stick," the AppleThunderboltNHI.kext file is restored automatically after restarting in normal mode, so I have followed the procedure which works according to many on the discussion referenced below.

Everything goes okay unless I do step 8, at which point the MacOS will not boot, I get a message like "...was restarted because of a problem..."

The only thing that seems to fix that, is to reinstall Big Sur from recovery mode, which does work. But then the AppleThunderboltNHI.kext file is restored.

I don't know is causing this procedure to fail. So I'm hoping someone might be able to help me solve it.

Note: The following instructions are not mine, and I am not recommending them as a solution.

https://developer.apple.com/forums/thread/666567?answerId=646500022#646500022

Posted by sf98723

Follow this procedure :

  1. Reboot in rescue mode (reboot while "Cmd + R")

  2. csrutil disable

  3. csrutil authenticated-root disable

  4. reboot in rescue mode

  5. mount -uw /Volumes/[MacOS ]

  6. delete (or rename, or move elsewhere) the AppleThunderboltNHI.kext directory (I've moved all thunderbolt kext directories since I have no needs about this interface, but I think it works only by disabling AppleThunderboltNHI)

  7. REBUILD the extensions cache ! (new has-to-do in Big Sur...) : kmutil install -u --force --volume-root /Volumes/[MacOS ]

  8. DON'T FORGET to create another system snapshot to take these modifications under account at next reboot : bless --folder /Volumes/[MacOS ]/System/Library/CoreServices --bootefi --create-snapshot

  9. csrutil enable (mays be you have to reboot in rescue mode.. not tested)

  10. Finally, reboot in normal mode

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  • What if your instructions are working and that kext is now needed to complete booting on Big Sur?
    – bmike
    Apr 30, 2021 at 11:44
  • I suppose that is possible, but from users on the Apple forum seem to have found a way to delete it and make it stay deleted. They all seem to agree that the key is making sure 'authenticated-root' stays disabled which is the point of steps 7&8. It is a hacky solution but the alternative is to buy a motherboard or leave a TB network adapter or dummy HDMI permanently attached to the computer.
    – Paul
    Apr 30, 2021 at 11:50
  • Have you disabled fileVault? This was a necessary step for me
    – Ycon
    Jun 30, 2021 at 0:57

1 Answer 1

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In addition to the comments, to address the "Everything goes okay unless I do step 8, at which point the macOS will not boot, I get a message like '...was restarted because of a problem...'" issue, you have to make sure the csrutil is enabled and authenticated-root is actually DISABLED. I made the mistake of enabling both after all the steps.

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  • It would be more proper if you put this as a comment to the related answer, and if that's not possible, wait until you have enough reputation points.
    – Alper
    Jan 5 at 10:09

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